1. Field of the Invention
The present invention relates to a holder and a structure for organizing excess length of cables and the like, and in particular to a holder and a structure for organizing excess length by winding cables and the like.
2. Description of the Related Art
In recent years, together with increased high-density mounting of devices (packages) with respect to transmission devices installed in station premises, areas for accommodating cables within a rack where the devices are stored are physically running short. For example, even in the absence of a problem of a circuitry function, restrictions on the number of devices mounted within a rack may be unavoidably required in some cases since cables cannot be accommodated due to a shortage of area within the rack.
It is to be noted that, in the following description, although a 2-core or 8-core optical code included in optical cables is mentioned as a specific example of a cable requiring excess length organizing in a rack of transmission devices, cables that can be organized or arranged are not limited to optical codes but include general types of cables such as metal cables (electric cables), and optical cables.
FIGS. 4A and 4B show an example of a conventional cable wiring structure within a rack. FIG. 4A shows a perspective view of a rack 100 partially showing the interior of the rack 100 in a state where a door 110 on the observer's left is shown as being open. As shown, a rack pillar 101 is provided to the rear of the inner surface of a rack side 102, and a holder 104 is fixed to the rack pillar 101. Also, the rack 100 is provided with a unit 103 for mounting a device 40.
An optical code 20 and a metal cable 30 drawn into the rack 100 within station premises from the outside of the station premises are respectively connected to the device 40. The length of the metal cable 30 can be adjusted by cutting if necessary. However, the light code 20 is obtained by removing a sheath of an optical cable (not shown) immediately before being drawn into the rack 100, and is usually cut up to a uniform length that reaches the device 40 mounted on the unit 103 at a highest position considering the height of the rack 100. Accordingly, it is general to organize an excess length by winding the optical code 20 around the holder 104 as required, thereby adjusting the length.
It is to be noted that in the following description, unless otherwise specified, the optical code 20, the metal cable 30, and the device 40 include a plurality of optical codes, metal cables, and devices.
FIG. 4B shows a sectional view along a line A–A′ of FIG. 4A showing a positional relationship between the rack pillar 101, the rack side 102, the unit 103, the holder 104, and the door 110. However, FIG. 4A shows a state where the door 110 is open, while FIG. 4B shows a state where the door 110 is closed.
An optical code area P shown in FIG. 4B is an area for accommodating the code 20. A metal code area Q is an area for accommodating the metal code 30. Also, a work area X for organizing optical code's excess length is a work area when an excess length organizing operation is performed by winding the optical code 20 around the holder 104. An organizing area Y of optical code's excess length is an area occupied by the optical code 20 wound around the holder 104.
Among these, the work area X for organizing optical code's excess length is an area required only when the excess length organizing operation is performed. However, since the holder 104 is fixed to the rack pillar 101, the work area X for organizing optical code's excess length always occupies a fixed area within the rack 100 as a result.
Apart from the rack 100 shown in FIGS. 4A and 4B, as an example of a device rack accommodating an optical fiber cable by organizing the excess length thereof, there is one that organizes the excess length by winding the optical fiber cable around a spool on a one-by-one basis, and fixes the spool on a supporting plate on a side surface to the front of the device rack, thereby allocating and accommodating the optical fiber cable (see e.g. patent document 1).
Another example is an optical cable connecting box. A cabinet having a cable fixing portion and a floor cable fixing portion is freely openably and closably provided with a door. The inside wall surface of the cabinet is equipped with a plurality of optical cable guides. Adapter guides are freely insertably and removably provided with adapter plates having a plurality of adapters connected to core wire ends branched from a trunk cable. An optical fiber tape core wire connected to a cable introduced from the cable fixing portion is branched via a single core separating portion to single core fibers. Termination wiring materials of conversion core wires having SC plugs or MPO plugs are connected to the other ends of the respective single core wires. In addition, the plugs are freely attachably and detachably connected to the adapters (see e.g. patent document 2).
Yet another example is an optical connecting box housing optical connectors for connecting optical fibers to other optical fibers and excess length storing portions for storing the excess length portions of the optical fibers in a box body of the optical connecting box. The box body has a main box body provided with an aperture and doors disposed at the main box body so as to make the aperture freely openable and closable. The excess length storing portions are provided on the inner side of at least one of the doors (see e.g. patent document 3).
[Patent document 1] Japanese patent application laid-open No. 11-23856
[Patent document 2] Japanese patent application laid-open No. 9-329716
[Patent document 3] Japanese patent application laid-open No. 10-20218
For example, as the number of ports increases in an IPoverSDH supporting device or the like, concerns have risen for mixing of metal cables (electric cables) on a LAN side and optical codes and the like on an SDH side. Specifically, when a device-accommodating rate increases, cable wirings become complicated.
Therefore, when a fault occurs in any one of the optical codes 20 in the rack 100 as shown in FIGS. 4A and 4B, it is difficult to identify the optical code 20 requiring treatment. Even if it can be identified, removing only one optical code 20 from the holder 104 separately from the other optical codes 20 is difficult. Therefore, in the worst case, there is no choice but to cut the optical code 20 requiring treatment. In this case, the normal optical codes 20 are not cut but only the optical code 20 requiring treatment is cut and a new optical code 20 is connected.
As the optical codes 20 increase in number, not only the excess length organizing operation itself becomes complicated but also the maintenance operation becomes more complicated as mentioned above.
Moreover, in order to enable more devices to be mounted inside a limited rack, it is desirable to secure a larger cable area so that more cables can be accommodated.